Basic operations of MySQL view

        mysql For an introduction to views and how to create them, please see ： A case study mysql View . This chapter mainly records the modification of view 、 Delete and display view syntax .

Catalog

One 、 Create view

Two 、 Modify the view

3、 ... and 、 Delete view

Four 、 Update the view

5、 ... and 、 Show the view

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One 、 Create view

        Please have a look at ： A case study mysql View

Two 、 Modify the view

         grammar ：alter view view_name as Modify the content

-- grammar     alter view view_name as    
--         Content 

alter view sms as 
select s_id,s_name
from student

 translate ： Will be with sms The content of the named view is modified to student In the table s_id and s_name

3、 ... and 、 Delete view

         grammar ：drop view view_name（ Collocation if exists Use , grammar ：drop view if exists view_name）

--  grammar 1 drop view view_name
drop view sms

--  grammar 2 drop view if exists view_name
drop view if exists sms

        

Four 、 Update the view

        The same view can also update data like a real table , But here's the thing Update the data in the view , It is also equivalent to updating the real table

        grammar ：UPDATE view_name set update_columns where  Conditions

#  Create a view student table 
create view view_student as 
select * 
from student

--  Update the view 
update view_student set s_id = 888 where s_name = ' Zhang San '

        Put the above sql After execution , Let's open two more tables （ View table  view_student, True table student）. We will find that these two tables meet the above where Conditions will change , In other words, updating the view will affect the original data in the real table .

        The following is a screenshot of the results before and after executing the update view statement ：

      original student and view_student                    After the update student                          After the update view_student

                          ​​​​​    

5、 ... and 、 Show the view

        grammar ：show create view view_name（ Used to query the details of a view ）

--  grammar ：show create view view_name
show create view sms

        The output is shown in the following figure ：